1. Field of the Invention
This invention relates to time division multiple access (TDMA) communication systems; and particularly to TDMA systems in which multiple radio stations communicate through an earth satellite repeater by transmitting time-synchronized bursts of radio energy relative to said repeater and receiving a time multiplex composite of bursts containing corresponding modulation information from said repeater.
2. Prior Art
Systems of radio communication using techniques of TDMA operation and TDMA/DA operation (DA referring to demand assignment) are well known.
In TDMA operation multiple transceiver stations associated with radio signaling nodes transmit bursts of time concentrated information signals on a shared carrier frequency spectrum and receive the same information signals after repetition by the satellite on a shifted carrier frequency spectrum. Each station is assigned particular time slots in a continuum of recurrent frames for transmission of its bursts and for reception of its own bursts and bursts of other stations. The bursts interleave at the satellite in close time formation without overlapping.
In DA operation lengths of assigned slots may be varied in accordance with the relative distribution of demand at the signaling nodes.
Various systems have been proposed for enabling stations operating in TDMA mode relative to different transponder frequency spectra to intercommunicate. Such proposed systems have been rejected for various reasons. Systems based upon time domain switching relative to transmission frequency spectra have been rejected as overly expensive and inefficient because of the magnitudes of transmission power which must be handled. Systems based upon simultaneous transmission on plural frequency bands at each node have been rejected as inefficient and overly complex.
The present invention concerns a system for providing intertransponder communication in TDMA mode which is efficient, inexpensive to implement relative to conventional unitransponder systems, and relatively simple to construct and operate.